v. throwing something together in order to complete a task quickly; doing an incomplete job or skipping steps in the process of a task
adj. a negative term decribing something that appears to have been done in a hap-slap manner; appearing as unsound, rough, or incomplete
syn. half-hearted, half-ass, unsound, untrustworthy, unstable, slack, sloppy

These days, developers often hap-slap houses together to make a quick buck.